New spiroaminoborate esters derived from 1,1-diphenylprolinol, ephedrine and dihydroquinine with different alkoxy substituents were prepared as stable crystalline compounds and characterized by spectroscopical analysis and specific rotation. The structure of the spiroborate 4 derived from 1,1-diphenylprolinol and dicyclohexyl-1,1'-diol was confirmed by X-ray analysis.
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| http://dx.doi.org/10.1016/j.tetlet.2011.12.054 | DOI Listing |
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Synthesis and stability of new spiroaminoborate esters.
Tetrahedron Lett
February 2012
Department of Chemistry, University of Puerto Rico - Humacao, Call Box 860, Humacao, Puerto Rico 00792, USA.
New spiroaminoborate esters derived from 1,1-diphenylprolinol, ephedrine and dihydroquinine with different alkoxy substituents were prepared as stable crystalline compounds and characterized by spectroscopical analysis and specific rotation. The structure of the spiroborate 4 derived from 1,1-diphenylprolinol and dicyclohexyl-1,1'-diol was confirmed by X-ray analysis.
View Article and Find Full Text PDFChiral epoxides via borane reduction of 2-haloketones catalyzed by spiroborate ester: application to the synthesis of optically pure 1,2-hydroxy ethers and 1,2-azido alcohols.
J Org Chem
March 2011
Department of Chemistry, University of Puerto Rico-H-umacao, CUH Station, Humacao, Puerto Rico 00791.
An enantioselective borane-mediated reduction of a variety of 2-haloketones with 10% spiroaminoborate ester 1 as catalyst is described. By a simple basic workup of 2-halohydrins, optically active epoxides are obtained in high yield and with excellent enantiopurity (up to 99% ee). Ring-opening of oxiranes with phenoxides or sodium azide is investigated under different reaction conditions affording nonracemic 1,2-hydroxy ethers and 1,2-azido alcohols with excellent enantioselectivity (99% ee) and in good to high chemical yield.
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Tetrahedron Asymmetry
December 2009
Department of Chemistry, University of Puerto Rico-Humacao, CUH Station Humacao, Puerto Rico 00791, USA.
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